The worldwide transition to lead-free electronics is forcing most major suppliers of electronic components to convert their product lines from tin/lead-containing finishes to lead-free finishes. As a result, most electronics suppliers have moved to pure electroplated tin finishes. However, there is a tendency of electroplated pure tin finishes to form tin whiskers that extend a distance from the surface. Such tin whiskers have been found to form on a wide variety of tin-plated components, and under a wide range of environmental conditions. Since these tin whiskers are comprised of nearly pure tin and are therefore electrically conductive, they can cause problems, such as, for example, shorting of electronic components. Therefore the growth of tin whiskers from tin-plated surfaces continues to cause reliability issues and other problems for electronic systems that use tin-plated components. Undesirable effects attributable to tin whisker formation on tin-plated surfaces have caused significant customer dissatisfaction resulting in significant financial impact on electronics manufacturers. To date, the only way to ensure that tin whiskers do not grow within an electronic system is to eliminate pure tin from such a system. However, the increasing reliance on the use of tin and tin-plated components in the electronic industry makes this tin elimination strategy unworkable. For example, a tin coating on components helps to protect the components from corrosion. Tin coatings also help to provide a suitable surface for soldering.
One tin whisker mitigation strategy has been to immerse all tin-plated component leads into molten tin/lead, from the tip of the lead up to the component body. However, this process can undesirably affect the component and is expensive to implement into the manufacturing process. Other systems have tried immersion plating or otherwise providing a metallic or non-metallic overcoat to tin surfaces. However, no known methods have provided predictable long-term economical, reproducible and scalable solutions to the eventual and undesirable whisker formation on tin-plated surfaces.